Summary Mental illness is a major public health concern in the U.S. and a significant source of morbidity and mortality. Racial and ethnic minority patients experience disproportionate burdens of common physical health conditions associated with mental illness, largely due to the lack of health care access and social stigma. Effectively treating mental illness and the associated conditions will depend on a comprehensive approach that crosses health systems and policies, such as the Community Benefit State Laws, to target ?Population Health? and emphasize the value of social determinants of health. However, the current mental health care system works in a silo, and evidence of care coordination on health disparities is lacking. The goal of this study is to examine system-level care coordination among hospitals, communities, and public health agencies, and to estimate its impacts on unmet health care needs in African American and Latino patients with mental illness. The rationale for the proposed research is that once it is known what specific coordination practices (e.g. medical services, transportation, public housing) and policies are most successful for different patient populations, integration of mental and physical health care delivery systems can be designed in a more cost-effective way to overcome the barriers from stigma and limited health care access. In this project, we will first determine the effects of Community Benefit State Laws on racial and ethnic disparities in health care access, quality, and costs among people with mental illness (Aim 1). Within this context, we will further identify the variation of hospital-based adoption of care coordination practices and its correlation with patient and community level socio- demographics, local public health resources, and the extent of the implementation of community benefit laws (Aim 2); and determine the impact of care coordination practices between hospitals, communities, and public health agencies on racial and ethnic health disparities (Aim 3). We will use mixed methods: (1) we will construct a multi-level data set by linking multiple nationally representative data sets and use difference-in- differences approach to estimate the impact of system-level care coordination on different racial/ethnic groups; and (2) we will investigate challenges to implementing system-level coordination using focus groups of racial and ethnic minority patient representatives, hospital administrators and providers, and representatives from public health agencies. The proposed research is significant because (1) identified practices are expected to provide evidence on how to personalize mental health care coordination for racial and ethnic minority patients to address heterogeneous preferences in mental health treatment; (2) identified system-level care coordination practices are expected to be cost-effective, which in turn can make the coordination sustainable for underserved populations. Our results are expected to break down longstanding silos and bridge the gap between health care providers, community based organizations, social service agencies, and the public health sector delivery system, in addition to providing evidence to reduce health disparities through care coordination.